Carbon Dioxide Equivalent Emissions of Newly Developed Rice Varieties

S Mohsen Taghavi ,Jauhar Ali,Tao Li,Zhikang Li,Sameer Ali Siddiq,T C Mendoza ,Jose M Yorobe ,Bart Acero

doi:10.5539/jas.v9n5p107

Abstract

Breeding of rice varieties with low carbon dioxide equivalent (CO2e) emission is essential in reducing global greenhouse gas (GHG) emissions. In this study, we compared the gross CO2e emission of two newly developed green super rice (GSR) varieties with elite hybrids and nationally released farmer-cultivated varieties from production to post-production in the dry and wet seasons in Laguna, Philippines. The average gross CO2e emission was 17.9 tons CO2e ha-1 or 2.98 tons CO2e ton-1 rice (production 82%, post-production 18%). Contributing to this total were soil emissions at 72%, the use of chemicals at 5%, burning of rice straw at 3%, cooking at 12%, and transportation at 5%. The average social cost of carbon (SCC) per ton of rice was estimated at $119. Increasing grain yield per unit area with shorter growth duration decreased CO2e emission of rice per unit of weight. Cultivation of rice varieties GSR8 and GSR2 emitted 37.0% lower CO2e than the popular inbred varieties.

Highlights

Rice CO2e emission is defined as the total set of greenhouse gases (GHG) emissions from a unit area of a rice field and is calculated as carbon dioxide equivalent (CO2e)
The wet season started in May and June, and cultivation finished by the end of October
Most of the farms were irrigated by canals and the farmer’s calendar was managed by the National Irrigation Administration (NIA)

Summary

Introduction

Rice CO2e emission is defined as the total set of GHG emissions from a unit area (ha) of a rice field and is calculated as carbon dioxide equivalent (CO2e). These GHGs include carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). Annual cereal production will increase to 3 billion tons from 2.1 billion tons in 2009, all of which need to be produced with reduced resources and without straining the environment (FAO, 2009) through the emission of greenhouse gases (GHG). In 2010, agriculture contributed 8.5 Gt CO2e yr-1 of GHG emission (FAO, 2009, IPCC, 2007). The largest contributors to agricultural emissions are enteric fermentation (38%), manure left on pasture (14%), synthetic fertilizer (13%), biomass burning (11%), rice cultivation (9%), manure management systems (7%), organic soils (5%), crop residues (3%), and manure applied to cropland (2%) (IPCC, 2007)

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Discussion

Conclusion